It's tough enough to find a job today without having to battle through obstacles you might not even know exist, but it could happen to you, as employers are increasingly using filters and machines to screen candidates.

A perceived challenge with these filters and machines when selecting candidates is that they might prevent employers from identifying the best workers for open positions – but even in a tight job market, this isn't curtailing their use.

Here are three major filters employers are using that you need to be aware of – and how to potentially deal with them.

1) Your social media profile is an open book. Don't fall victim to the following mistake. You've deeply researched your potential new role but you forgot to clean up your social media profile. That questionable party photo or controversial, swear-laden political tweet could very well be the reason why you weren't considered for the position.

Using machines and artificial intelligence, many employers are conducting social media scans of their prospective hires. Before you start applying for jobs, take a good, clear-eyed and dispassionate look at how you present yourself online. You might even have a friend or colleague (whose judgment you trust) do a review for you.

And while you're at it – make sure your profile is up to date and you've got a professional photo showing. Unless you are in a highly creative field, the glamour shots and unorthodox poses just don't work on a more serious, job-oriented platform. You run the risk of making an impression that doesn't help your case.

2) Employers are prying into your salary history. This can put you in a very unfair position as a job seeker. Plus – it's uncomfortable and awkward. As the person selling yourself and your skills, you want to ideally be in the best possible position to secure fair compensation.

The good news on the salary front is that several cities and states, such as Massachusetts, New York City, Philadelphia and New Jersey, are now exploring new laws (or have already passed laws) that would prevent employers from asking about pay history.

But until it's a thing of the past everywhere, it pays to be aware that you may very likely be asked about your past salary history, and that employers can use it as a "hidden screen" when considering you for a job.

This is what happens when your potential employers go outside the set of references you shared to talk to others you've worked with. More often than not, this will work out fine for you … but not always. The possibility exists that an employer finds that one boss or colleague – often through social media – who you didn't leave with the best of impressions.

Here are some of the ways to deal with the problem of backdoor references:

Be aware that backdoor references are a real phenomenon.

Take a careful look at your social networks and cull them down if needed – eliminate the wild cards.

Check in with former managers who may not be your references but you suspect could be contacted, just to get a feel for where you stand.

If you think you could be asked about an issue raised by a backdoor reference – be prepared with a rehearsed response.

Concentrate on developing a list of stellar "real references" who can tell your story well.

So with all of these external factors suddenly and unpredictably influencing your job search, what can you do?

The burden falls even more to you. It's up to you to paint the most accurate picture of yourself across every step of the application process.

Develop a top-quality resume. Make sure you have well-researched and prepared interview interactions every time. And build up a list of great job references. Your references can speak on your behalf even better than you can for yourself. They can overcome the inaccuracies and misperceptions that any of these external "job filters" might inject into the discussion.

No matter what screens an employer may try to use, there's no screen than can undo the positive influence of the factors you control yourself during your job hunt. So make the most of them.